1. Field of the Invention
This invention relates to an output apparatus such as a printing machine and a display device that are capable of producing after performing compression and extension effectively on character patterns, and to a method of processing outputs.
2. Related Background Art
Conventionally in a so-called dictionary (indexing) based compression method, a set of characters where one character is formed of bit patterns of M rows by N columns is divided for each character into a submatrix of M1 rows by N1 columns and performing indexing (assigning a same number to submatrices having the same dot patterns) on all of said submatrices to represent the character divided into said M1 rows by N1 columns by an index number associated with each submatrix, thereby M1 by N1 bits of the submatrix is compressed into bit numbers (generally a multiple of 8) used in the index number.
As the actual compressed data, a dot pattern tables (dictionaries) are required that are arranged in the indexing order along with the compressed data represented by the index numbers.
In addition, in the character pattern output apparatus of the type described that is known conventionally, a character font pattern comprising no print dot as the font data, i.e., a blank font is stored in the same manner as for the normal character fonts.
However, the above mentioned related art has the following disadvantages.
More specifically, in the related art, the indexing is performed for compression on the submatrix that is appeared only once in all submatrices, so that more storage is required than the original data by the number of bits (index bits) used in the index number to such submatrix (because the size of the M1 by N1 bits submatrix stored in the dot pattern table is constant regardless of the time of references).
In addition, one numeral is assigned to the submatrix that is referred only once, so that the increased number of numerals are required for indexing, increasing the index bits. Accordingly, there is a defect that the compression efficiency is extremely bad for compression of patterns containing many matrices of this type.
Further, there is a disadvantage of waste because the actual submatrix pattern should be referred from the index number even for the submatrix that is referred only once during extension, as for the submatrix referred two or more times.
Moreover, in the conventional art, an index number storing region is fixed length, so that the compression efficiency is extremely bad because the number of bits used in the index number is increased for those having many patterns such as kanji fonts.
On the other hand, as for a proportional font used in the alphanumeric fonts, a font box is adapted to those having the largest character width, so that a space is developed in the conventional art for those containing a small character.
In addition, according to a method of storage in the conventional art, the kanji fonts defined by JIS contain many space or blank fonts where no print dot is contained, so that such space fonts results in the increased storage region, with many wastes, in printers or CRTs in recent years where highly accurate fine production is required.